Water cooler



FIG. 1 is a top perspective view of a water cooler showing my new design;

FIG. 2 is a front elevational view thereof;

FIG. 3 is a side elevational view thereof;

FIG. 4 is a top plan thereof;

FIG. 5 is a bottom view thereof; and,

FIG. 6 is a rear view thereof.

The broken lines in the drawings are included for the purpose of illustration and form no part of the claimed design. 

The ornamental design for a water cooler, as shown and described. 